Process for treating flue dust



March 6, 1928. K. M. SIMPSON PROCESS FOR TREATING FLUE DUST Filed April7. 1926 '4: Q?

3 m If. M aim $6011 Patented Mar. 6, 1928.

UNITED STATES KENNETH M. SIMPSON, OF NEW YORK, Y.

PROCESS FOR TREATING FLUE DUST.

Application fi1ed Apri1 7,

The invention relates to improvements in a process for producing toughand hard charges for blast and other smelting furnaces.

Among its many objects the invention aims to provide a process whereinthe flue dustfrom blast furnaces and the like may be so treated as toprovide a most useful change for such furnaces or others of a similarcharacter. It has been long recognized that this dust contains valuableores, carbonaceous matter and the like, but up to the present time thisdust has largely been a waste. product because of the failure of priorart processes to adequately handle the same. While the invention ishighly applicable. to the treatment of this material, it is alsoapplicable in connection with the treatment of flotation concentratesand other materials in an exceedingly fine state of subdivision.

Primarily the invention embodies a process in which the fine flue dustor other material containing ores, etc., is mixed with finely pulverizedcoal or coke and a hydrocarbon oil,the mixture 'being baked in thepresence of air to harden the oil by oxidation and provide the toughfirm masses which may be used with most satisfactory results, as chargesfor blast and other smelting furnaces.

In carrying out the process I collect the flue dust discharging from ablast furnace, containing a substantial quantity of ore which, ofcourse, largely depends upon the material being treated by the furnace,as

well as fine coke, etc. This material I collect and then thoroughly mixwith an added charge of finely pulverized coal or coke. The substancesare then thoroughly inter- 40 mingled with coke oven tar or the like inthe proportion of about 16 per cent of the amount of mixture in the formof the tar.

- These materials are then thoroughly mixed.

The mixed substances may then be briquetted at a pressure of say 2500pounds per square inch in any conventional form of roll press. This stepis preferable, although not necessary. The resulting briquettes arequite hard or firm and are then placed m any kiln or oven of any wellknown type and heated to a temperature of say 350 Fl This heat treatmentoccurs in the presence of air, thereby causing the oil and thebriquettes to be thoroughly oxidized. The time required for this bakingtreatment naturally varies,

1926. Seria1N0.100,4 54.

but I have found that in most cases a period of four hours issufficient. It will be understood that the. oil distilled from thebriquettes during this treatment may be recovered from the condensers inany well known manner. The briquettes after this described treatment arethen placed in a second continuously operated kiln or retort and fromthis retort air is excluded. The temperature of this retort is raised tosay 1000 F., the briquettes being maintained at this temperature forapproximately one hour. Practi-' cally all of the oil is thus removedfrom the briquettes. The resulting briquettes are very tough and hardand constitute excellent charges for blast and other smelting furnaces.p y

The ore content of the briquettes may, of course, vary and consist ofsuch materials as zinc, lead, and copper ores, as well as various ironores. It will likewise be appreciated that the preparation of pulverizedcoal or coke in each briquette may also vary between wide limits,although the proportion of oil will not materially vary because it isthe residual carbon of the oil resulting from the oxidation anddistillation thereof that acts as a cementing material to bind the oiland fuel particles together.

For ordinary commercial work the briquettes should carry from 5 to 50per cent coke, the amount being determined by the nature of the oreparticles contained in the briquettes and the demands of the smeltingoperation. For instance, in the case of iron flue dust, I use generallyfrom 30 to 40 per cent coke,'w.hile in the case of copper concentrates 5per cent coke may be sufficient as the sulphur in the copper mineralfurnishes the bulk of the fuel. q

At times when dealing with certain ores no pulverized coke may be used.In fact, I may mix the finely pulverized ore-concentrates with oil tarand form the mixture into briquettes in the manner I have hereinbeforeset forth.

In the figure of the drawing I have shown I diagrammatically anapparatus for supporting this process.

In the drawing the numeral 1 designates a briquetting belt having aseries of pockets 2 therein, the walls of which are preferablyperforated. A briquetting roller 3 cooperates with this belt to placethe material fed to the pockets into the shoe 4 under a high state ofcompression. The belt then travels through the initial heating furnacewhere the briquettes in the pockets 2 thereof are heated in the presenceof air admitted through the air controlled line 5. A furnace 6 isemployed for heating this oven gas or light fuel being admitted theretothrough the line 7. The gaseous roducts escape from the oven through t eline 8, pass through a condenser 9 where the condensable products arecondensed, and collected in the container 10. From this containeruncondenscd substances may be discharged through the valve controlledline 11. The partially treated briquettes are then discharged upon aplatform 12.

From the platform 12 the briquettes are introduced to the oven 13. Theyare placed on movable platforms 14 which may be insertedin the oven 13and removed therefrom by opening or closing the door 15. Air is excludedfrom this oven so that the briquettes 16 are baked therein under a hightemperature with no air being present. From the oven 13 gaseous productsescape through the valve controlled line 17 to a suitable condenser 18and thence to a container 19 which is of the same construction as thecontainer 10.

Having thus described my invention, what I claim is:

1. The herein described rocess which comprises mixing with flue ustpulverized carbonaceous fuel matter, in adding to such mass ahydrocarbon, in briquetting the resulting mixture, in' subjecting themixed materials to a carbonizing treatment in which the volatiles of thehydrocarbon are largely removed and the solid materials bonded by thecarbon residue thereof by preliminarily heating the material in a zonewhere oxygen is present, and in thereafter raising the temperature ofthe material in a zone where oxygen is excluded.

2. A process for agglomeratin materials containing minerals insubstantia quantities in pulverized form consisting in mixing with saidminerals a liquid hydrocarbon, in first baking the mixture in thepresence of air and in recovering the products of distillation andthereafter subjecting the material to higher temperature treatment inthe absence of air to form a tou h, hard briquette and in condensing andco lecting the products distilled during this second treatment.

In testimony whereof I afiix my signature.

KENNETH M. SIMPSON.

